Despite the high incidence of neuropathic and inflammatory pain worldwide, effective drugs with few side effects are currently unavailable for the treatment of chronic pain. Recently, researchers have proposed that inhibitors of purinergic chemical transmission, which plays a key role in the pathological pain response, may allow for targeted treatment of pathological neuropathic and inflammatory pain. However, such therapeutic analgesic agents have yet to be developed. In the present study, we demonstrated that clodronate, a first-generation bisphosphonate with comparatively fewer side effects than traditional treatments, significantly attenuates neuropathic and inflammatory pain unrelated to bone abnormalities via inhibition of vesicular nucleotide transporter (VNUT), a key molecule for the initiation of purinergic chemical transmission. In vitro analyses indicated that clodronate inhibits VNUT at a halfmaximal inhibitory concentration of 15.6 nM without affecting other vesicular neurotransmitter transporters, acting as an allosteric modulator through competition with Cl − . A low concentration of clodronate impaired vesicular ATP release from neurons, microglia, and immune cells. In vivo analyses revealed that clodronate is more effective than other therapeutic agents in attenuating neuropathic and inflammatory pain, as well as the accompanying inflammation, in wild-type but not VNUT −/− mice, without affecting basal nociception. These findings indicate that clodronate may represent a unique treatment strategy for chronic neuropathic and inflammatory pain via inhibition of vesicular ATP release. vesicular nucleotide transporter | purinergic chemical transmission | analgesic effect | antiinflammatory effect | clodronate

Objective: Mitochondria consistently change their morphology in a process regulated by proteins, including Drp1 (dynamin-related protein 1), a protein promoting mitochondrial fission. Drp1 is involved in the mechanisms underlying various cardiovascular diseases, such as myocardial ischemia/reperfusion injury, heart failure, and pulmonary arterial hypertension. However, its role in macrophages, which promote various vascular diseases, is poorly understood. We therefore tested our hypothesis that macrophage Drp1 promotes vascular remodeling after injury. Method and Results: To explore the selective role of macrophage Drp1, we created macrophage-selective Drp1-deficient mice and performed femoral arterial wire injury. In these mice, intimal thickening and negative remodeling were attenuated at 4 weeks after injury when compared with control mice. Deletion of macrophage Drp1 also attenuated the macrophage accumulation and cell proliferation in the injured arteries. Gain- and loss-of-function experiments using cultured macrophages indicated that Drp1 induces the expression of molecules associated with inflammatory macrophages. Morphologically, mitochondrial fission was induced in inflammatory macrophages, whereas mitochondrial fusion was induced in less inflammatory/reparative macrophages. Pharmacological inhibition or knockdown of Drp1 decreased the mitochondrial reactive oxygen species and chemotactic activity in cultured macrophages. Co-culture experiments of macrophages with vascular smooth muscle cells indicated that deletion of macrophage Drp1 suppresses growth and migration of vascular smooth muscle cells induced by macrophage-derived soluble factors. Conclusions: Macrophage Drp1 accelerates intimal thickening after vascular injury by promoting macrophage-mediated inflammation. Macrophage Drp1 may be a potential therapeutic target of vascular diseases.

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Background and Aims: It is currently unclear whether sodium–glucose co-transporter 2 (SGLT2) inhibitor administration can improve the insulin sensitivity as well as rapidly reduce plasma glucose concentrations in humans during the early phase of treatment initiation. This study aimed to investigate the effect of SGLT2 inhibitor on insulin sensitivity in the early phase of treatment initiation. Methods and Results This single-center, open label, and single-arm prospective study recruited 20 patients (14 men) with type 2 diabetes mellitus (T2DM). We examined the patients’ metabolic parameters before and 1 week after SGLT2 inhibitor (10 mg/day of empagliflozin) administration. The glucose infusion rate (GIR) was evaluated using the euglycemic hyperinsulinemic glucose clamp technique. Changes in laboratory and anthropometric parameters before and after SGLT2 inhibitor administration were analyzed according to the change in the GIR. The BMI, body fat amount, skeletal muscle amount, systolic blood pressure, and triglyceride level significantly decreased along with the treatment, while urinary glucose level and log GIR value significantly increased. Notably, changes in the GIR after SGLT2 inhibitor administration, which indicated improvement in peripheral insulin sensitivity, were negatively correlated with T2DM duration and positively with reduction in fluctuation of daily plasma glucose profiles before and after treatment. Conclusion SGLT2 inhibitor improved insulin sensitivity in the skeletal muscle independent of anthropometric changes. Patients with short duration of T2DM and insulin resistance can be good candidates for short-term SGLT2 inhibitor administration to improve insulin sensitivity in the skeletal muscle.