UNASSIGNED: Metformin treatment attenuates experimental abdominal aortic aneurysm (AAA) formation, as well as reduces clinical AAA diameter enlargement in patients with diabetes. The mechanisms of metformin-mediated aneurysm suppression, and its efficacy in suppressing established experimental aneurysms, remain uncertain.
UNASSIGNED: Experimental AAAs were created in male C57BL/6J mice via intra-aortic infusion of porcine pancreatic elastase. Metformin alone (250 mg/kg), or metformin combined with the 5\' AMP-activated protein kinase (AMPK) antagonist Compound C (10 mg/kg), were administered to respective mouse cohorts daily beginning 4 days following AAA induction. Further AAA cohorts received either the AMPK agonist AICA riboside (500 mg/kg) as positive, or vehicle (saline) as negative, controls. AAA progression in all groups was assessed via serial in vivo ultrasonography and histopathology at sacrifice. Cytokine-producing T cells and myeloid cellularity were determined by flow cytometric analyses.
UNASSIGNED: Metformin limited established experimental AAA progression at 3 (-85%) and 10 (-68%) days following treatment initiation compared with saline control. Concurrent Compound C treatment reduced this effect by approximately 50%. In metformin-treated mice, reduced AAA progression was associated with relative elastin preservation, smooth muscle cell preservation, and reduced mural leukocyte infiltration and neoangiogenesis compared with vehicle control group. Metformin also resulted in reduced interferon-γ-, but not interleukin-10 or -17, producing splenic T cells in aneurysmal mice. Additionally, metformin therapy increased circulating and splenic inflammatory monocytes (CD11b+Ly-6Chigh), but not neutrophils (CD11b+Ly-6G+), with no effect on respective bone marrow cell populations.
UNASSIGNED: Metformin treatment suppresses existing experimental AAA progression in part via AMPK agonist activity, limiting interferon-γ-producing T cell differentiation while enhancing circulating and splenic inflammatory monocyte retention.

Th2 immune cells infiltration into nasal mucosa is one of the characters of allergic rhinitis (AR). We aimed to explore whether inhibition of Th2 immune cells infiltration would attenuate AR progression. AR mouse model was established by i.p. injection of ovalbumin (OVA). The infiltrated immune cells into nasal lavage fluid were detected by flow cytometry. Cytokine concentration in serum was determined by ELISA. AR mice symptoms were indicated by the number of sneezing and nasal rubbing events. In AR mice, CCL2 expression levels and CD45+CD11b+Ly6Chi inflammatory monocytes cells significantly increased as compared with control mice. CCL2 siRNA encapsulated nanoparticles (NPsiCCL2) prevent CCL2 expression and inflammatory monocytes infiltration in AR mice. NPsiCCL2 treatment dramatically decreased the number of sneezing and nasal rubbing events in AR mice. Moreover, NPsiCCL2 treatment attenuated serum OVA-specific IgE, OVA-specific IgG1 and histamine levels. Mechanically, NPsiCCL2 treatment attenuates AR symptoms via inhibiting Th2 cytokine (IL-4, IL-5 and IL-13) production. Nanomedicine-mediated prevention of inflammatory monocytes infiltration ameliorates ovalbumin-induced allergic rhinitis in mouse model.

Recent studies have reported recruitment of inflammatory monocytes by cytokines including chemokine (C-C motif) ligand 2 (CCL2) are critical in allergic responses. We aimed to investigate the role of inflammatory monocytes and CCL2 in mouse model with ovalbumin (OVA)-induced allergic asthma. Mice were sensitized with OVA to induce allergic asthma. The proportion of inflammatory cells in bronchoalveolar lavage fluid (BALF) and peritoneal lavage fluid (PLF) were measured by flow cytometry. The expression of CCL2 and CCL2 receptor (CCR2) were determined by qPCR and western blot. The concentrations of Type 1 helper T (Th1) and Type 2 helper T (Th2) cytokines in PLF were detected by ELISA. Inflammatory monocytes are recruited in PLF, and expression of CCL2 and CCR2 were elevated in OVA-induced mice. In addition, transfer of CCR2 knockdown inflammatory monocytes decreased the levels of allergic asthma biomarkers. Injection of anti-CCL2 or anti-CCR2 antibody decreased the proportion of eosinophils and inflammatory monocytes in BALF. Blockade of CCL2/CCR2 signaling pathway suppressed the allergen-induced Th2 cytokines and enhanced the levels of Th1-associated cytokines. Blockade of CCL2/CCR2 signaling pathway in sensitization-recruited inflammatory monocytes exhibits protective effects in mouse model of OVA-induced allergic asthma by inhibiting the Th2 inflammatory responses.

The activation of Toll-like receptor (TLR) signaling is widely reported to be involved in preventing the development of allergic asthma. However, the mechanism of the protective function of TLR signaling remains limited. Here, we studied the mouse model of ovalbumin (OVA)-induced allergic asthma and found that deficiency of TLR signaling or activating TLR signaling with agonist would aggravate or attenuate OVA-induced allergic asthma, respectively, and TLR signaling-mediated protective effect mainly affected the sensitization phase. After OVA/alum sensitization, neutrophils and inflammatory monocytes were recruited into peritoneal cavity and up-regulated TLRs expression. However, adoptive transfer of inflammatory monocytes but not peritoneal macrophages or neutrophils induced allergic symptoms in recipient mice after OVA challenge even without OVA/alum sensitization, and treating the inflammatory monocytes with TLR agonist in vitro before transfer could abolish this effect, indicating that recruited inflammatory monocytes played a determinant role in OVA-induced allergic asthma, and activation of TLR signaling in them could attenuate allergic symptoms. Finally, we found that activation of TLR signaling could increase the expression of T-helper (Th) 1-associated cytokines in inflammatory monocytes. Our results suggest that activation of TLR signaling in sensitization-recruited inflammatory monocytes attenuates OVA-induced allergic asthma by promoting the expression of Th1-associated cytokines.

Reactive oxygen species have been demonstrated to involve in homocysteine-induced Ly-6Chi monocytes differentiation. Probucol is an anti-oxidant agent that has been used to treat atherosclerosis. We sought to evaluate the effect and potential mechanism of probucol on homocysteine-induced inflammatory monocytes differentiation. The primary mouse splenocytes suspensions were initiated by recombinant interferon-γ and cultured with L-homocysteine in the presence or absence of probucol. The cells were co-incubated with monoclonal antibodies to CD11b-PE and Ly-6C FITC. Flow cytometry analysis was performed on BD FACS caliber. Data were analyzed using the FlowJo software. Mononuclear cells were gated according to the lower granular and larger size, distinguished with granulocytes and lymphocytes. Monocytes were defined as CD11b+ mononuclear cells and further divided into three groups based on their Ly-6C expressions, Ly-6Chi, Ly-6Cmid and Ly-6Clow subsets. The productions of reactive oxygen species in monocytes subsets were detected by 2\',7\'-dichlorofluorescein-diacetate (DCFH-DA) containing monocytes were marked as DCFH-DA+ cells in both Ly-6C+ and Ly-6C- subsets. The activity of nicotinamide adenine dinucleotide phosphate oxidase in THP-1 cells was measured by assay kit on enzyme-labelling instrument. L-homocysteine promoted inflammatory monocytes differentiation and its reactive oxygen species productions in dose-dependent manner. Probucol dose-dependently suppressed the differentiation and reactive oxygen species productions of inflammatory monocytes induced by L-homocysteine. Furthermore, the increased NADPH oxidase activity induced by L-homocysteine was significantly reversed by probucol in THP-1 cells. Probucol prevented L-homocysteine-induced inflammatory monocytes differentiation and its reactive oxygen species generation probably through inhibiting NADPH oxidase activity.

Circulating cell-free DNA (cfDNA) has been widely suggested as clinical indicator in diseases, including sepsis. It was thought that the cfDNA was coming from the cell lysis, necrosis and apoptosis caused by tissue damages during sepsis. M1 or M2 macrophage-type responses kill or repair in vivo, which is highly relevant with the tissue damages in sepsis. The correlation between cfDNA and M1/M2 responses during sepsis was never investigated. Here, we used bacteria injection induced septic peritonitis mouse model in both M1-dominant C57bl/6 and M2-dominant Balb/c mouse strains. We found that M2-dominant Balb/c mice showed better prognosis of septic peritonitis than C57bl/6 mice, which is corresponded with lower level of cfDNA in septic Balb/c mice compared to septic C57bl/6 mice. By assessing the M1 and M2 related cytokines in both septic Balb/c and C57bl/6 mice, we found out that Balb/c mice has lower tumor necrosis factor α (TNFα) and higher interleukin 10 (IL-10) productions than C57bl/6 mice during septic peritonitis. Especially, when monitoring the monocyte subtypes in peripheral blood of these septic mice, we found out that C57bl/6 showed higher inflammatory (Ly6C(high)) monocyte (corresponding to M1 macrophage) proportion than Balb/c mice. Interestingly, we find out that cfDNA is highly correlated with the ratio of Ly6C(high) monocytes versus Ly6C(low) monocytes, which represents M1/M2 (killing/healing) responses. Our study suggested that the cfDNA is a good indicator for evaluating M1/M2 responses in septic peritonitis.