Obesity and associated metabolic diseases are characterized by a chronic low-grade inflammatory state with the infiltration of many inflammatory cells, especially macrophages. Immune molecules, including some cytokines, have a close relationship with metabolism. Interleukin (IL)-25 is a member of the IL-17 cytokine family that can regulate macrophages and alleviate some metabolic dysfunction; however, its role and mechanisms in lipid metabolism remain to be extensively clarified. Human serum and liver biopsy specimens, high-fat diet-induced obesity mice and DB/DB (Lepr−/−) animal models were used to examine IL-25 expression in obesity and nonalcoholic fatty liver diseases (NAFLD). To observe the role of IL-25 in lipid metabolism, model mice were administered with IL-25 or adoptively transferred with IL-25-educated macrophages in vivo, whereas bone marrow-derived macrophages, the macrophage cell line RAW264.7 and adipocytes differentiated from 3T3-L1 were used in vitro. IL-25 was decreased in NAFLD patients and obese mice. In addition, IL-25 reduced body weight gain and lipid accumulation, enhanced lipid uptake by macrophages and increased the expression of lipolysis and β-oxidation enzymes via alternatively activating macrophages. IL-25 also promoted lipolysis and suppressed lipogenesis in adipocytes co-cultured with the IL-25-educated macrophages. Furthermore, IL-25 improved the mitochondrial respiratory capacity and oxygen consumption rate of macrophages and produced more NAD⁺/NADH and ATP. In conclusion, IL-25 can stimulate M2 macrophage polarization and thereby promote lipolysis and mitochondrial respiratory capacity, highlighting the potential for IL-25 to be used as a therapeutic agent against obesity and associated metabolic syndromes.

Purpose.: The authors' previous studies showed that the Wnt signaling pathway is activated in the retinas and retinal pigment epithelia of animal models of age-related macular degeneration (AMD) and diabetic retinopathy (DR). The purpose of this study was to investigate the role of the canonical Wnt pathway in pathogenesis of these diseases. Methods.: The Wnt pathway was activated using the Wnt3a-conditioned medium and adenovirus expressing a constitutively active mutant of β-catenin (Ad-S37A) in ARPE19, a cell line derived from human RPE. Ad-S37A was injected into the vitreous of normal rats to activate the Wnt pathway in the retina. Accumulation of β-catenin was determined by Western blot analysis, and its nuclear translocation was revealed by immunocytochemistry. Inflammatory factors were quantified by Western blot analysis and ELISA. Oxidative stress was determined by measuring intracellular reactive oxygen species (ROS) generation and nitrotyrosine levels. Results.: The Wnt3a-conditioned medium and Ad-S37A both increased β-catenin levels and its nuclear translocation in ARPE19 cells, suggesting activation of the canonical Wnt pathway. Activation of the Wnt pathway significantly upregulated the expression of VEGF, NF-κB, and TNF-α. Further, Ad-S37A induced ROS generation in a dose-dependent manner. Wnt3a also induced a twofold increase of ROS generation. Intravitreal injection of Ad-S37A upregulated the expression of VEGF, ICAM-1, NF-κB, and TNF-α and increased protein nitrotyrosine levels in the retinas of normal rats. Conclusions.: Activation of the canonical Wnt pathway is sufficient to induce retinal inflammation and oxidative stress and plays a pathogenic role in AMD and DR.

Diabetic foot ulcer (DFU) caused by impaired wound healing is a common vascular complication of diabetes. The current study revealed that plasma levels of pigment epithelium–derived factor (PEDF) were elevated in type 2 diabetic patients with DFU and in db/db mice. To test whether elevated PEDF levels contribute to skin wound-healing delay in diabetes, endogenous PEDF was neutralized with an anti-PEDF antibody in db/db mice. Our results showed that neutralization of PEDF accelerated wound healing, increased angiogenesis in the wound skin, and improved the functions and numbers of endothelial progenitor cells (EPCs) in the diabetic mice. Further, PEDF-deficient mice showed higher baseline blood flow in the skin, higher density of cutaneous microvessels, increased skin thickness, improved numbers and functions of circulating EPCs, and accelerated wound healing compared with wild-type mice. Overexpression of PEDF suppressed the Wnt signaling pathway in the wound skin. Lithium chloride–induced Wnt signaling activation downstream of the PEDF interaction site attenuated the inhibitory effect of PEDF on EPCs and rescued the wound-healing deficiency in diabetic mice. Taken together, these results suggest that elevated circulating PEDF levels contribute to impaired wound healing in the process of angiogenesis and vasculogenesis through the inhibition of Wnt/β-catenin signaling.

Gastric cancer and breast cancer have a clear tendency toward metastasis and invasion to the microenvironment predominantly composed of adipocytes. Oleic acid is an abundant monounsaturated fatty acid that releases from adipocytes and impinges on different energy metabolism responses. The effect and underlying mechanisms of oleic acid on highly metastatic cancer cells are not completely understood. We reported that AMP-activated protein kinase (AMPK) was obviously activated in highly aggressive carcinoma cell lines treated by oleic acid, including gastric carcinoma HGC-27 and breast carcinoma MDA-MB-231 cell lines. AMPK enhanced the rates of fatty acid oxidation and ATP production and thus significantly promoted cancer growth and migration under serum deprivation. Inactivation of AMPK attenuated these activities of oleic acid. Oleic acid inhibited cancer cell growth and survival in low metastatic carcinoma cells, such as gastric carcinoma SGC7901 and breast carcinoma MCF-7 cell lines. Pharmacological activation of AMPK rescued the cell viability by maintained ATP levels by increasing fatty acid β-oxidation. These results indicate that highly metastatic carcinoma cells could consume oleic acid to maintain malignancy in an AMPK-dependent manner. Our findings demonstrate the important contribution of fatty acid oxidation to cancer cell function.

Significance: CRC patients with KRAS mutations are confronted with limited targeted therapeutic options. In this study, we have shown that the median survival time for KRAS -mutation mCRC patients with diabetes on metformin is 37.8 mo longer than those treated with other hypoglycemic drugs in combination with standard systemic therapy. Metformin is preferentially accumulated in KRAS -mutation CRC cells in both primary cell cultures and patient-derived xenografts. The promising therapeutic activity of metformin has a negative correlation with MATE1 expression, which is proven to eliminate metformin from CRC cells. These findings indicate that KRAS -mutation mCRC patients could benefit from metformin treatment, and somatic KRAS status or MATE1 expression should be recommended to predict the therapeutic response of metformin in CRC.

The accumulation of M1-polarized macrophages and excessive inflammation are important in the pathogenesis of diabetic foot ulcer (DFU). However, the underlying mechanism of DFU pathogenesis and the crucial regulators of DFU are less well known. Our previous study reported that kallikrein-binding protein (KBP), an angiogenesis inhibitor, was significantly upregulated in diabetic patients compared to its levels in controls. The effects of KBP on monocyte chemotaxis and macrophage M1 polarization were elucidated in this study. Plasma KBP levels and monocyte counts were assessed by ELISA and flow cytometry. Wound closure rates in different groups were monitored daily. The phenotype and recruitment of macrophages were measured by real-time PCR, western blot and immunofluorescence assays. The expression of Notch and NF-κB signalling pathway members was determined by the methods mentioned above. ChIP and dual-luciferase reporter gene assays were employed to explore the binding and transcriptional regulation of Hes1 and iNOS. We found that plasma KBP levels and circulating monocytes were elevated in diabetic patients compared to those in nondiabetic controls, and both were higher in diabetic patients with DFU than in diabetic patients without DFU. KBP delayed wound healing in normal mice; correspondingly, KBP-neutralizing antibody ameliorated delayed wound healing in diabetic mice. Circulating monocytes and macrophage infiltration in the wound were upregulated in KBP-TG mice compared to those in control mice. KBP promoted the recruitment and M1 polarization of macrophages. Mechanistically, KBP upregulated iNOS by activating the Notch1/RBP-Jκ/Hes1 signalling pathway. Hes1 downregulated CYLD, a negative regulator of NF-κB signalling, and then activated the IKK/IκBα/NF-κB signalling pathway. Our findings demonstrate that KBP is the key regulator of excessive inflammation in DFUs and provide a novel target for DFU therapy.