GLUT3 promotes macrophage signaling and function via RAS-mediated endocytosis in atopic dermatitis and wound healing.

The facilitative GLUT1 and GLUT3 hexose transporters are expressed abundantly in macrophages, but whether they have distinct functions remains unclear. We confirmed that GLUT1 expression increased after M1 polarization stimuli and found that GLUT3 expression increased after M2 stimulation in macrophages. Conditional deletion of Glut3 (LysM-Cre Glut3fl/fl) impaired M2 polarization of bone marrow-derived macrophages. Alternatively activated macrophages from the skin of patients with atopic dermatitis showed increased GLUT3 expression, and a calcipotriol-induced model of atopic dermatitis was rescued in LysM-Cre Glut3fl/fl mice. M2-like macrophages expressed GLUT3 in human wound tissues as assessed by transcriptomics and costaining, and GLUT3 expression was significantly decreased in nonhealing, compared with healing, diabetic foot ulcers. In an excisional wound healing model, LysM-Cre Glut3fl/fl mice showed significantly impaired M2 macrophage polarization and delayed wound healing. GLUT3 promoted IL-4/STAT6 signaling, independently of its glucose transport activity. Unlike plasma membrane-localized GLUT1, GLUT3 was localized primarily to endosomes and was required for the efficient endocytosis of IL-4Rα subunits. GLUT3 interacted directly with GTP-bound RAS in vitro and in vivo through its intracytoplasmic loop domain, and this interaction was required for efficient STAT6 activation and M2 polarization. PAK activation and macropinocytosis were also impaired without GLUT3, suggesting broader roles for GLUT3 in the regulation of endocytosis. Thus, GLUT3 is required for efficient alternative macrophage polarization and function, through a glucose transport-independent, RAS-mediated role in the regulation of endocytosis and IL-4/STAT6 activation.

Optimal management of esophageal cancer in Africa: A systemic review of treatment strategies.

Esophageal cancer (EC) is a leading cause of cancer morbidity and mortality in Africa. Despite the high burden of disease, optimal management strategies for EC in resource-constrained settings have yet to be established. This systematic review evaluates the literature on treatments for EC throughout Africa and compares the efficacy and safety of varying treatment strategies in this context (PROSPERO CRD42017071546). PubMed, Embase and African Index Medicus were searched for studies published on treatment strategies for EC in Africa from 1980 to 2020. Searches were supplemented by examining bibliographies of included studies and relevant conference proceedings. Methodological quality/risk of bias was assessed using the Cochrane Risk-of-Bias tool and the Newcastle-Ottawa Scale. Forty-six studies were included. Case series constituted the majority of studies: 13 were case series reporting on outcomes of esophagectomies, 17 on palliative luminal or surgical interventions, four on radiotherapy and three on concurrent chemoradiation. Nine randomized controlled trials were identified, of which four prospectively compared different treatment modalities (one investigating radiotherapy vs chemoradiation, three evaluating rigid plastic stents vs other treatments). This review summarizes the research on EC treatments in Africa published over the last four decades and outlines critical gaps in knowledge related to management in this context. Areas in need of further research include (a) evaluation of the safety and efficacy of neoadjuvant therapy in patients with locally advanced disease; (b) strategies to improve long-term survival in patients treated with definitive chemoradiation; and (c) the comparative effectiveness of modern palliative interventions, focusing on quality of life and survival as outcome measures.