Chiral Aldehyde-Palladium Catalysis Enables Asymmetric Synthesis of α-Alkyl Tryptophans via Cascade Heck-Alkylation Reaction.

The first catalytic asymmetric cascade Heck-alkylation reaction of NH2-unprotected amino acid esters with N-(2-iodophenyl)allenamides is reported in this work. Under the promotion of a combining catalytic system comprising a chiral aldehyde, a chiral palladium complex, and the Lewis acid ZnCl2, the title reaction takes place smoothly, giving optically active α-alkyl tryptophan derivatives in moderate to good yields and excellent enantioselectivities. The target products can be converted into other structurally complex chiral indoles without the loss of enantioselectivities.

Risk factors of lymph node metastasis or lymphovascular invasion for superficial esophageal squamous cell carcinoma: A practical and effective predictive nomogram based on a cancer hospital data.

Background: Lymphovascular invasion (LVI) is mostly used as a preoperative predictor to establish lymph node metastasis (LNM) prediction models for superficial esophageal squamous cell carcinoma (SESCC). However, LVI still needs to be confirmed by postoperative pathology. In this study, we combined LNM and LVI as a unified outcome and named it LNM/LVI, and aimed to develop an LNM/LVI prediction model in SESCC using preoperative factors. Methods: A total of 512 patients who underwent radical resection of SESCC were retrospectively collected. Logistic regression and least absolute shrinkage and selection operator (LASSO) regression were adopted to identify the predictive factors of LNM/LVI. Integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were calculated to select the potential predictive factors from the results of LASSO and logistic regression. A nomogram for predicting LNM/LVI was established by incorporating these factors. The efficacy, accuracy, and clinical utility of the nomogram were, respectively, assessed with the area under the curve (AUC), calibration curve, and decision curve analysis (DCA). Finally, the random forest (RF) algorithm was used to further evaluate the impact of these factors included in the nomogram on LNM/LVI. Results: Tumor size, tumor location, tumor invasion depth, tumor differentiation, and macroscopic type were confirmed as independent risk factors for LNM/LVI according to the results of logistic regression, LASSO regression, IDI, and NRI analyses. A nomogram including these five variables showed a good performance in LNM/LVI prediction (AUC = 0.776). The calibration curve revealed that the predictive results of this nomogram were nearly consistent with actual observations. Significant clinical utility of our nomogram was demonstrated by DCA. The RF model with the same five variables also had similar predictive efficacy with the nomogram (AUC = 0.775). Conclusion: The nomogram was adopted as a final tool for predicting LNM/LVI because its risk score system made it more user-friendly and clinically useful than the random forest model, which can help clinicians make optimal treatment decisions for patients with SESCC.

A Novelly Developed Bipolar Needle Knife Can Be an Alternative Device Choice for Endoscopic Submucosal Dissection (With Video).

Background: Endoscopic submucosal dissection (ESD) is technically difficult with high rates of complications, such as perforation and bleeding. We aimed to explore the safety and cutting efficiency of a novelly devised bipolar knife for ESD procedure. Methods: Taking a traditional monopolar knife as a reference, the safety and feasibility of the novel bipolar knife were evaluated by an animal experiment and a human study. Furthermore, we assessed the usefulness and advantage of this novel bipolar knife by using the finite element method. Results: A porcine experiment confirmed that there was no significant difference in wound size and cutting speed between the monopolar and bipolar knives. The thermal damage and histopathological scores produced by the two knives were similar. In addition, the porcine experiment and patients' study identified that the incidence of postoperative complications, such as bleeding, perforation, and infection, had no statistical difference between the monopolar and bipolar groups. Finally, the finite element model showed that the length and depth of thermal damage caused by the bipolar knife were, respectively, 102.77-117.98% and 80.87-84.53% of those caused by the monopolar knife at the same power. Conclusion: The novel bipolar knife was theoretically safer than the monopolar knife and, at least, was confirmed not inferior to the monopolar knife in operability and cutting efficiency. Thus, the novel bipolar knife can be an alternative device choice for ESD.

Catalytic asymmetric Tsuji-Trost α-benzylation reaction of N-unprotected amino acids and benzyl alcohol derivatives.

Catalytic asymmetric Tsuji-Trost benzylation is a promising strategy for the preparation of chiral benzylic compounds. However, only a few such transformations with both good yields and enantioselectivities have been achieved since this reaction was first reported in 1992, and its use in current organic synthesis is restricted. In this work, we use N-unprotected amino acid esters as nucleophiles in reactions with benzyl alcohol derivatives. A ternary catalyst comprising a chiral aldehyde, a palladium species, and a Lewis acid is used to promote the reaction. Both mono- and polycyclic benzyl alcohols are excellent benzylation reagents. Various unnatural optically active α-benzyl amino acids are produced in good-to-excellent yields and with good-to-excellent enantioselectivities. This catalytic asymmetric method is used for the formal synthesis of two somatostatin mimetics and the proposed structure of natural product hypoestestatin 1. A mechanism that plausibly explains the stereoselective control is proposed.

Epiregulin as an Alternative Ligand for Leptin Receptor Alleviates Glucose Intolerance without Change in Obesity.

The leptin receptor (LepR) acts as a signaling nexus for the regulation of glucose uptake and obesity, among other metabolic responses. The functional role of LepR under leptin-deficient conditions remains unclear. This study reports that epiregulin (EREG) governed glucose uptake in vitro and in vivo in Lepob mice by activating LepR under leptin-deficient conditions. Single and long-term treatment with EREG effectively rescued glucose intolerance in comparative insulin and EREG tolerance tests in Lepob mice. The immunoprecipitation study revealed binding between EREG and LepR in adipose tissue of Lepob mice. EREG/LepR regulated glucose uptake without changes in obesity in Lepob mice via mechanisms, including ERK activation and translocation of GLUT4 to the cell surface. EREG-dependent glucose uptake was abolished in Leprdb mice which supports a key role of LepR in this process. In contrast, inhibition of the canonical epidermal growth factor receptor (EGFR) pathway implicated in other EREG responses, increased glucose uptake. Our data provide a basis for understanding glycemic responses of EREG that are dependent on LepR unlike functions mediated by EGFR, including leptin secretion, thermogenesis, pain, growth, and other responses. The computational analysis identified a conserved amino acid sequence, supporting an evolutionary role of EREG as an alternative LepR ligand.

"Pink Pattern" Visualized in Magnifying Endoscopy With Narrow-Band Imaging Is a Novel Feature of Early Differentiated Gastric Cancer: A Bridge Between Endoscopic Images and Histopathological Changes.

Background: A pink color change occasionally found by us under magnifying endoscopy with narrow-band imaging (ME-NBI) may be a special feature of early gastric cancer (EGC), and was designated the "pink pattern". The purposes of this study were to determine the relationship between the pink pattern and the cytopathological changes in gastric cancer cells and whether the pink pattern is useful for the diagnosis of EGC. Methods: The color features of ME-NBI images and pathological images of cancerous gastric mucosal surfaces were extracted and quantified. The cosine similarity was calculated to evaluate the correlation between the pink pattern and the nucleus-to-cytoplasm ratio of cancerous epithelial cells. Two diagnostic tests were performed by 12 endoscopists using stored ME-NBI images of 185 gastric lesions to investigate the diagnostic efficacy of the pink pattern for EGC. The diagnostic values, such as the area under the curve (AUC), the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), of test 1 and test 2 were compared. Results: The cosine similarity between the color values of ME-NBI images and pathological images of 20 lesions was at least 0.744. The median AUC, accuracy, sensitivity, specificity, PPV, and NPV of test 2 were significantly better than those of test 1 for all endoscopists and for the junior and experienced groups. Conclusions: The pink pattern observed in ME-NBI images correlated strongly with the change in the nucleus-to-cytoplasm ratio of gastric epithelial cells, and could be considered a useful marker for the diagnosis of differentiated EGC.

Retrospective analysis of predictive factors for lymph node metastasis in superficial esophageal squamous cell carcinoma.

This study aimed to identify the risk factors of lymph node metastasis (LNM) in superficial esophageal squamous cell carcinoma and use these factors to establish a prediction model. We retrospectively analyzed the data from training set (n = 280) and validation set (n = 240) underwent radical esophagectomy between March 2005 and April 2018. Our results of univariate and multivariate analyses showed that tumor size, tumor invasion depth, tumor differentiation and lymphovascular invasion were significantly correlated with LNM. Incorporating these 4 variables above, model A achieved AUC of 0.765 and 0.770 in predicting LNM in the training and validation sets, respectively. Adding macroscopic type to the model A did not appreciably change the AUC but led to statistically significant improvements in both the integrated discrimination improvement and net reclassification improvement. Finally, a nomogram was constructed by using these five variables and showed good concordance indexes of 0.765 and 0.770 in the training and validation sets, and the calibration curves had good fitting degree. Decision curve analysis demonstrated that the nomogram was clinically useful in both sets. It is possible to predict the status of LNM using this nomogram score system, which can aid the selection of an appropriate treatment plan.

A Nomogram for Predicting Lymphovascular Invasion in Superficial Esophageal Squamous Cell Carcinoma.

The lymphovascular invasion (LVI) status facilitates the determination of the optimal therapeutic strategy for superficial esophageal squamous cell carcinoma (SESCC), but in clinical practice, LVI must be confirmed by postoperative pathology. However, studies of the risk factors for LVI in SESCC are limited. Consequently, this study aimed to identify the risk factors for LVI and use these factors to establish a prediction model. The data of 516 patients who underwent radical esophagectomy between January 2007 and September 2019 were retrospectively collected (training set, n=361, January 2007 to May 2015; validation set, n=155, June 2015 to September 2019). In the training set, least absolute shrinkage and selection operator (LASSO) regression and multivariate analyses were utilized to identify predictive factors for LVI in patients with SESCC. A nomogram was then developed using these predictors. The area under the curve (AUC), calibration curve, and decision curve were used to evaluate the efficiency, accuracy, and clinical utility of the model. LASSO regression indicated that the tumor size, depth of invasion, tumor differentiation, lymph node metastasis (LNM), sex, circumferential extension, the presence of multiple lesions, and the resection margin were correlated with LVI. However, multivariate analysis revealed that only the tumor size, depth of invasion, tumor differentiation, and LNM were independent risk factors for LVI. Incorporating these four variables, model 1 achieved an AUC of 0.817 in predicting LVI. Adding circumferential extension to model 1 did not appreciably change the AUC and integrated discrimination improvement, but led to a significant increase in the net reclassification improvement (p=0.011). A final nomogram was constructed by incorporating tumor size, depth of invasion, tumor differentiation, LNM, and circumferential extension and showed good discrimination (training set, AUC=0.833; validation set, AUC=0.819) and good calibration in the training and validation sets. Decision curve analysis demonstrated that the nomogram was clinically useful in both sets. Thus, it is possible to predict the status of LVI using this nomogram scoring system, which can aid the selection of an appropriate treatment plan.

Direct Catalytic Asymmetric α-Allylic Alkylation of Aza-aryl Methylamines by Chiral-Aldehyde-Involved Ternary Catalysis System.

A ternary catalytic system comprising a chiral aldehyde, a transition metal, and a Lewis acid is rationally designed for the asymmetric α-allylic alkylation reaction of aza-aryl methylamines and π-allylmetal electrophiles. Structural diversity chiral amines bearing carbon-carbon double bonds and aza-heterocycles are produced in moderate to good yields with good to excellent enantioselectivities. These products can be readily converted into other chiral amines without the loss of enantioselectivity. A reasonable reaction mechanism is proposed to illustrate the stereoselective control results.

Epiregulin induces leptin secretion and energy expenditure in high-fat diet-fed mice.

Adipokine leptin regulates neuroendocrine circuits that control energy expenditure, thermogenesis and weight loss. However, canonic regulators of leptin secretion, such as insulin and malonyl CoA, do not support these processes. We hypothesize that epiregulin (EREG), a growth factor that is secreted from fibroblasts under thermogenic and cachexia conditions, induces leptin secretion associated with energy dissipation. The effects of EREG on leptin secretion were studied ex vivo, in the intra-abdominal white adipose tissue (iAb WAT) explants, as well as in vivo, in WT mice with diet-induced obesity (DIO) and in ob/ob mice. These mice were pair fed a high-fat diet and treated with intraperitoneal injections of EREG. EREG increased leptin production and secretion in a dose-dependent manner in iAb fat explants via the EGFR/MAPK pathway. After 2 weeks, the plasma leptin concentration was increased by 215% in the EREG-treated group compared to the control DIO group. EREG-treated DIO mice had an increased metabolic rate and core temperature during the active dark cycle and displayed cold-induced thermogenesis. EREG treatment reduced iAb fat mass, the major site of leptin protein production and secretion, but did not reduce the mass of the other fat depots. In the iAb fat, expression of genes supporting mitochondrial oxidation and thermogenesis was increased in EREG-treated mice vs control DIO mice. All metabolic and gene regulation effects of EREG treatment were abolished in leptin-deficient ob/ob mice. Our data revealed a new role of EREG in induction of leptin secretion leading to the energy expenditure state. EREG could be a potential target protein to regulate hypo- and hyperleptinemia, underlying metabolic and immune diseases.

Induction of innervation by encapsulated adipocytes with engineered vitamin A metabolism.

Innervation is a fundamental basis for function and survival of tissues. In the peripheral tissues, degenerative diseases create a neurotoxic metabolic milieu that either causes neurodegeneration or fails to sustain regenerative growth and reinnervation of injured/diseased tissues. Encapsulation of cells producing neurotrophic factors can augment axon growth and neuron survival; however, sustained innervation in vivo requires a combination of factors promoting axon growth and guidance pathway that are released in a tissue-specific context. Using novel encapsulation techniques and genetic tools, we manipulated retinoic acid-generating enzyme aldehyde dehydrogenase 1a1 (Aldh1a1) in adipocytes that are capable of promoting growth and innervation of white adipose tissue by sympathetic neurons. Aldh1a1-/- adipocytes secrete molecules that regulate axon guidance and markedly stimulate neurite outgrowth in vitro and in vivo. Based on studies with natural and synthetic RAR agonists and antagonists, gene microarray and nanostring arrays, we concluded that ephrin A5/ephrin A4 is a downstream pathway regulated by Aldh1a1. Encapsulation of Aldh1a1-/- adipocytes into alginate poly-L-lysine microcapsules induced functional innervation of adipose tissue in obese wild-type mice. We propose that encapsulated Aldh1a1-/- adipocytes could provide a therapeutic solution for the reinnervation of damaged tissues.

A Novel Saccadic Strategy Revealed by Suppression Head Impulse Testing of Patients with Bilateral Vestibular Loss.

OBJECTIVE: We examined the eye movement response patterns of a group of patients with bilateral vestibular loss (BVL) during suppression head impulse testing. Some showed a new saccadic strategy that may have potential for explaining how patients use saccades to recover from vestibular loss. METHODS: Eight patients with severe BVL [vestibulo-ocular reflex (VOR) gains less than 0.35 and absent otolithic function] were tested. All patients were given the Dizziness Handicap Inventory and questioned about oscillopsia during abrupt head movements. Two paradigms of video head impulse testing of the horizontal VOR were used: (1) the classical head impulse paradigm [called head impulse test (HIMPs)]-fixating an earth-fixed target during the head impulse and (2) the new complementary test paradigm-fixating a head-fixed target during the head impulse (called SHIMPs). The VOR gain of HIMPs was quantified by two algorithms. RESULTS: During SHIMPs testing, some BVL patients consistently generated an inappropriate covert compensatory saccade during the head impulse that required a corresponding large anti-compensatory saccade at the end of the head impulse in order to obey the instructions to maintain gaze on the head-fixed target. By contrast, other BVL patients did not generate this inappropriate covert saccade and did not exhibit a corresponding anti-compensatory saccade. The latencies of the covert saccade in SHIMPs and HIMPs were similar. CONCLUSION: The pattern of covert saccades during SHIMPs appears to be related to the reduction of oscillopsia during abrupt head movements. BVL patients who did not report oscillopsia showed this unusual saccadic pattern, whereas BVL patients who reported oscillopsia did not show this pattern. This inappropriate covert SHIMPs saccade may be an objective indicator of how some patients with vestibular loss have learned to trigger covert saccades during head movements in everyday life.

Aldehyde dehydrogenase 1 a1 regulates energy metabolism in adipocytes from different species.

BACKGROUND: Survival and longevity of xenotransplants depend on immune function and ability to integrate energy metabolism between cells from different species. However, mechanisms for interspecies cross talk in energy metabolism are not well understood. White adipose tissue stores energy and is capable of mobilization and dissipation of energy as heat (thermogenesis) by adipocytes expressing uncoupling protein 1 (Ucp1). Both pathways are under the control of vitamin A metabolizing enzymes. Deficient retinoic acid production in aldehyde dehydrogenase 1 A1 (Aldh1a1) knockout adipocytes (KO) inhibits adipogenesis and increases thermogenesis. Here we test the role Aldh1a1 in regulation of lipid metabolism in xenocultures. METHODS: Murine wide-type (WT) and KO pre-adipocytes were encapsulated into a poly-L-lysine polymer that allows exchange of humoral factors <32kD via nanopores. Encapsulated murine adipocytes were co-incubated with primary differentiated canine adipocytes. Then, expression of adipogenic and thermogenic genes in differentiated canine adipocytes was detected by real-time polymerase chain reaction (PCR). The regulatory factors in WT and KO cells were identified by comparison of secretome using proteomics and in transcriptome by gene microarray. RESULTS: Co-culture of encapsulated mouse KO vs WT adipocytes increased expression of peroxisome proliferator-activated receptor gamma (Pparg), but reduced expression of its target genes fatty acid binding protein 4 (Fabp4), and adipose triglyceride lipase (Atgl) in canine adipocytes, suggesting inhibition of PPARγ activation. Co-culture with KO adipocytes also induced expression of Ucp1 in canine adipocytes compared to expression in WT adipocytes. Cumulatively, murine KO compared to WT adipocytes decreased lipid accumulation in canine adipocytes. Comparative proteomics revealed significantly higher levels of vitamin A carriers, retinol binding protein 4 (RBP4), and lipokalin 2 (LCN2) in KO vs WT adipocytes. CONCLUSIONS: Our data demonstrate the functional exchange of regulatory factors between adipocytes from different species for regulation of energy balance. RBP4 and LCN2 appear to be involved in the transport of retinoids for regulation of lipid accumulation and thermogenesis in xenocultures. While the rarity of thermogenic adipocytes in humans and dogs precludes their use for autologous transplantation, our study demonstrates that xenotransplantation of engineered cells could be a potential solution for the reduction in obesity in dogs and a strategy for translation to patients.

Saccadic Velocity in the New Suppression Head Impulse Test: A New Indicator of Horizontal Vestibular Canal Paresis and of Vestibular Compensation.

OBJECTIVE: To determine whether saccadic velocity in the suppression head impulse paradigm (SHIMP) test is a reliable indicator of vestibular loss at the acute and at the chronic stage in patients suffering from different vestibular pathologies. METHODS: Thirty-five normal subjects and 57 patients suffering from different vestibular pathologies associated with unilateral vestibular loss (UVL) or bilateral vestibular loss (BVL) were tested in the SHIMPs paradigm. SHIMPs were performed by turning the head 10 times at high velocities to the left or right side, respectively. The patients were instructed to fixate on a red spot generated by a head-fixed laser projected on the wall. In this SHIMPs paradigm, healthy subjects made a large anti-compensatory saccade at the end of the head turn (a SHIMP saccade). The peak saccadic velocity, the percentage of the trials completed with saccades in 10 trials, and the latency of the saccades were quantified in each group. A video-head impulse test (v-HIT) was systematically performed in all of our subjects as well as a caloric test. The dizziness handicap inventory questionnaire was also given to chronic UVL and BVL patients. RESULTS: At the acute stage after a complete UVL, patients had zero or a few anti-compensatory saccades for low velocity head turns toward the lesioned side. These saccades had lower velocity than the anti-compensatory saccades recorded during head rotation toward the intact side and/or compared with the saccades measured in control subjects. At the chronic stage, some of the patients recovered the ability to perform SHIMP saccades at each head turn toward the lesioned side, but very often these saccades were of significantly lower velocity. In BVL patients, no anti-compensatory saccades, or only significantly smaller ones, could be detected for head turns to both sides. CONCLUSION: SHIMP is a specific and sensitive test to detect a complete horizontal canal loss at the acute stage. In addition, it reflects the ability of patients with moderate horizontal vestibulo-ocular reflex gain decrease to generate anti-compensatory saccades in the chronic stage. In association with v-HIT, it allows determination of the residual vestibular function and to detect anti-compensatory saccades.

[Research progress of TRPV4 and cerebral ischemic reperfusion injury].

Transient receptor potential vanilloid 4 (TRPV4) channel is a member of transient receptor potential superfamily. TRPV4 is selectively permeable to calcium. Activation of the TRPV4 channel induces an increase in intracellular calcium concentration and plays an important role under physiological and pathological conditions. Especially, there is evidence showing that TRPV4 is involved in cerebral ischemic reperfusion injury. The present paper reviewed some research progress about the role of TRPV4 in cerebral ischemic reperfusion injury.

Encapsulation Thermogenic Preadipocytes for Transplantation into Adipose Tissue Depots.

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular weight metabolites in tissues of the treated host to achieve long-term survival. The semipermeable membrane allows engrafted encapsulated cells to avoid rejection by the immune system. The encapsulation procedure was designed to enable a controlled release of bioactive compounds, such as insulin, other hormones, and cytokines. Here we describe a method for encapsulation of catabolic cells, which consume lipids for heat production and energy dissipation (thermogenesis) in the intra-abdominal adipose tissue of obese mice. Encapsulation of thermogenic catabolic cells may be potentially applicable to the prevention and treatment of obesity and type 2 diabetes. Another potential application of catabolic cells may include detoxification from alcohols or other toxic metabolites and environmental pollutants.

Egg yolks inhibit activation of NF-κB and expression of its target genes in adipocytes after partial delipidation.

How composition of egg yolk (EY) influences NF-κB, a key transcription pathway in inflammation, remains unclear. We performed partial delipidation of EY that removed 20-30% of cholesterol and triglycerides. The resulting polar and nonpolar fractions were termed EY-P and EY-NP. NF-κB activation in response to EY from different suppliers and their fractions was examined in 3T3-L1 adipocytes using a NF-κB response element reporter assay and by analyzing expression of 248 inflammatory genes. Although EY-P and EY contained similar level of vitamins, carotenoids, and fatty acids, only delipidated EY-P fraction suppressed NF-κB via down-regulation of toll like receptor-2 and up-regulation of inhibitory toll interacting protein (Tollip) and lymphocyte antigen 96 (Ly96). Our data suggest that anti-inflammatory activity of lutein and retinol were blunted by nonpolar lipids in EY, likely via crosstalk between SREBP and NF-κB pathways in adipocytes. Thus, moderate delipidation may improve the beneficial properties of regular eggs.

Adipocyte reporter assays: application for identification of anti-inflammatory and antioxidant properties of mangosteen xanthones.

SCOPE: Three fluorescence biosensors were developed based on a 3T3-L1 preadipocyte line that stably expressed Nfkb-RE/GFP, Fabp4-P/CFP, and Nrf2-P/YFP fluorescent reporters. We hypothesized that nutraceuticals' inflammatory, adipogenic, and antioxidant status will be identified based on the change in fluorescence in reporter adipocytes. We validated these assays with activators of NFκB, FABP4-regulating peroxisome proliferator activated receptor gamma, NFR2 and, thereafter, tested known and unknown properties of mangostines (MGs), the xanthone metabolites in mangosteen fruit. METHODS AND RESULTS: We validated inflammatory and adipogenic properties of α-MG using an Nfkb-RE/GFP biosensor assay. Next, we identified unique properties of γ-MG, a minor MG xanthone. γ-MG suppressed adipogenesis and expression of adiponectin, but inhibited the Nfkb-RE/GFP reporter and secretion of inflammatory monocyte chemotactic protein 1 as compared to the control adipocytes. We found that the inhibition of adipogenesis and Nfkb-mediated inflammation depends on a dose-dependent reduction of Nrf2 promoter activity by α-MG. The Nrf2 inhibition resulted in the reduced Pparg expression. α-MG did not directly influence Pparg activity in Fabp4-P/CFP adipocytes. CONCLUSION: α-MG-mediated antioxidant response via Nrf2 is a mechanism preventing adipogenesis and inflammation in adipocytes. Combined application of high-throughput biosensors could provide an effective platform for the identification of nutraceuticals and the mechanism of their actions in adipocytes and, potentially, in obese patients.

Zinc deficiency augments leptin production and exacerbates macrophage infiltration into adipose tissue in mice fed a high-fat diet.

Zinc (Zn) deficiency and obesity are global public health problems. Zn deficiency is associated with obesity and comorbid conditions that include insulin resistance and type 2 diabetes. However, the function of Zn in obesity remains unclear. Using a mouse model of combined high-fat and low-Zn intake (0.5-1.5 mg/kg), we investigated whether Zn deficiency exacerbates the extent of adiposity as well as perturbations in metabolic and immune function. C57BL/6 mice were randomly assigned to receive either a high-fat diet (HFD) or a control (C) diet for 6 wk, followed by further subdivision into 2 additional groups fed Zn-deficient diets (C-Zn, HFD-Zn), along with a C diet and an HFD, for 3 wk (n = 8-9 mice/group). The extent of visceral fat, insulin resistance, or systemic inflammation was unaffected by Zn deficiency. Strikingly, Zn deficiency significantly augmented circulating leptin concentrations (HFD-Zn vs. HFD: 3.15 ± 0.16 vs. 2.59 ± 0.12 µg/L, respectively) and leptin signaling in the liver of obese mice. Furthermore, gene expression of macrophage-specific markers ADAM8 (A disintegrin and metalloproteinase domain-containing protein 8) and CD68 (cluster of differentiation 68) was significantly greater in adipose tissue in the HFD-Zn group than in the HFD group, as confirmed by CD68 protein analysis, indicative of increased macrophage infiltration. Inspection of Zn content and mRNA profiles of all Zn transporters in the adipose tissue revealed alterations of Zn metabolism to obesity and Zn deficiency. Our results demonstrate that Zn deficiency increases leptin production and exacerbates macrophage infiltration into adipose tissue in obese mice, indicating the importance of Zn in metabolic and immune dysregulation in obesity.