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Myeloid-derived suppressor cells (MDSCs) are heterogeneous myeloid cell populations with immunosuppressive capacity, which contribute to immune regulation and tolerance induction. We previously reported impaired MDSC function in patients with primary Sjögren’s syndrome (pSS) and mice with experimental SS (ESS). However, the molecular mechanisms underlying MDSCs dysfunction remain largely unclear. In this study, we first found that aryl hydrocarbon receptor (AhR) was highly expressed by human and murine polymorphonuclear MDSCs (PMN-MDSCs). Indole-3-propionic acid (IPA), a natural AhR ligand produced from dietary tryptophan, significantly promoted PMN-MDSC differentiation and their suppressive function on CD4+ T cells. In contrast, feeding tryptophan-free diet resulted in decreased PMN-MDSC response, a phenotype that could be reversed by IPA supplementation. The functional importance of PMN-MDSCs was demonstrated in ESS mice by cell-depletion approach. Notably, AhR expression was reduced in PMN-MDSCs during ESS development, while AhR antagonism resulted in exacerbated ESS pathology and dysregulated T effector cells, which could be phenocopied by tryptophan-free diet. Interferon regulatory factor 4 (IRF4), a repressive transcription factor, was upregulated in PMN-MDSCs during ESS progression. Chromatin immunoprecipitation analysis revealed the binding capacity of IRF4 to the promoter region of AhR, while IRF4 deficiency markedly enhanced AhR-mediated PMN-MDSC responses. Furthermore, dietary supplementation of IPA markedly ameliorated salivary glandular pathology in ESS mice with restored MDSC immunosuppressive function. Together, our results identify a novel function of AhR in modulating PMN-MDSC response and demonstrate the therapeutic potential of targeting AhR for the treatment of pSS.

Consumption of a modern Western-type high-fat low-fiber diet increases the risk of obesity. However, how a host responds to such a diet, especially during the early period of dietary transition from a previous low-fat and fiber-rich diet, remains poorly explored.Wild-type C57BL/6 mice were fed a normal chow diet or a high-fat diet. Enteric glial cell (EGC) activation was detected through quantitative real-time PCR (qRT-PCR), immunoblotting and immunohistology analysis. Fluorocitrate or genetic deletion of glial fibrillary acidic protein (GFAP)-positive glial-intrinsic myeloid differentiation factor 88 (Myd88) was used to inhibit EGC activation, and the effect of a high-fat diet on obesity was further investigated. The role of MYD88-dependent sensing of commensal products in adipocyte was observed to analyze the effect of obesity.A dietary shift from a normal chow diet to a high-fat diet in mice induced a transient early-phase emergence of a GFAP-positive EGC network in the lamina propria of the ileum, accompanied with an increase in glial-derived neurotrophic factor production. Inhibition of glial cell activity blocked this response. GFAP-positive glial Myd88 knockout mice gained less body weight after high-fat diet (HFD) feeding than littermate controls. In contrast, adipocyte deletion of Myd88 in mice had no effect on weight gain but instead exacerbated glucose intolerance. Furthermore, short-term fluorocitrate intervention during HFD feeding attenuated body weight gain.Our findings indicate that EGCs are early responders to intestinal ecosystem changes and the GFAP-positive glial Myd88 signaling participates in regulating obesity.

Propofol is the most commonly used sedative in gastrointestinal endoscopic procedures, but is associated with cardiorespiratory suppression, particularly in elderly patients. Remimazolam is a new short-acting GABA(A) receptor agonist with minimal impact on cardiorespiratory suppression, and may be a viable alternative in elderly patients undergoing endoscopic procedures.This multicenter, randomized controlled trial was conducted between September 2020 and September 2021. Elderly patients (65-85 years of age) scheduled to undergo upper gastrointestinal endoscopy were randomized in 1:1 ratio to receive remimazolam tosilate (300 mg/h) or propofol (3 g/h) in addition to 50-μg fentanyl, until the Modified Observer's Assessment of Alertness/Sedation Scale (MOAA/S) reached ≤1. MOAA/S was maintained at 0 or 1 throughout the procedure using 2.5 mg remimazolam or 0.5 mg/kg propofol boluses in the two groups, respectively. The primary outcome was the rate of hypotension (defined as systolic blood pressure at ≤90 mmHg or 30% decline vs. the baseline). Bradycardia was defined as heart rate ≤50 per minute; respiratory depression was defined as respiratory rate8 per minute and/or SpOA total of 400 patients (161 men and 239 women; 70.4 ± 4.6 years of age) were enrolled (200 patients per group). Average body mass index was 22.2 ± 2.4 kg/mRemimazolam was associated with a lower rate of hypotension in elderly patients undergoing upper gastrointestinal endoscopy under deep sedation/anaesthesia than propofol.

The iron (Fe) metabolism plays important role in regulating systemic metabolism and obesity development. The Fe inside cells can form iron-sulfur (Fe-S) clusters, which are usually assembled into target proteins with the help of a conserved cluster assembly machinery. Family with sequence similarity 96A (FAM96A; also designated CIAO2A) is a cytosolic Fe-S assembly protein involved in the regulation of cellular Fe homeostasis. However, the biological function of FAM96A in vivo is still incompletely defined. Here, we tested the role of FAM96A in regulating organismal Fe metabolism, which is relevant to obesity and adipose tissue homeostasis. We found that in mice genetically lacking FAM96A globally, intracellular Fe homeostasis was interrupted in both white and brown adipocytes, but the systemic Fe level was normal. FAM96A deficiency led to adipocyte hypertrophy and organismal energy expenditure reduction even under nonobesogenic normal chow diet-fed conditions. Mechanistically, FAM96A deficiency promoted mechanistic target of rapamycin (mTOR) signaling in adipocytes, leading to an elevation of de novo lipogenesis and, therefore, fat mass accumulation. Furthermore, it also caused mitochondrial defects, including defects in mitochondrial number, ultrastructure, redox activity, and metabolic function in brown adipocytes, which are known to be critical for the control of energy balance. Moreover, adipocyte-selective FAM96A knockout partially phenocopied global FAM96A deficiency with adipocyte hypertrophy and organismal energy expenditure defects but the mice were resistant to high-fat diet-induced weight gain. Thus, FAM96A in adipocytes may autonomously act as a critical gatekeeper of organismal energy balance by coupling Fe metabolism to adipose tissue homeostasis.

Glucose homeostasis of adipocytes could be regulated by immune-adipose crosstalk. In order to investigate the effects of Lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells (LIGHT) on glucose metabolism, we performed the present study. Our results showed that LIGHT deficiency improved glucose tolerance and enhanced glucose consumption of inguinal white adipose tissue (iWAT) under high fat diet. Consistently, Light overexpression could inhibit glucose uptake during the process of white adipogenesis. Mechanistically, LIGHT interacted with lymphotoxin-β receptor (LTβR) to attenuate AKT pathway leading to downregulation of glucose transporter-4 (GLUT4) expression, which resulted in glucose uptake inhibition. In summary, our findings revealed LIGHT-LTβR-AKT-GLUT4 axis as a regulator of glucose uptake in adipose tissue, which suggested the pivotal role of LIGHT in maintaining glucose homeostasis.

Evidence for transcatheter aortic valve implantation (TAVI) is scarce among patients with non-calcific aortic stenosis, and it is not known whether aortic valve calcification is associated with new cerebral ischemic lesions (CILs) that are detected by diffusion-weighted magnetic resonance imaging. So, our study enrolled 328 patients who underwent transfemoral TAVI using a self-expanding valve between December 2016 and June 2021 from the TORCH registry (NCT02803294). A total of 34 patients were finally confirmed as non-calcific AS and the remaining 294 patients were included in the calcific AS group. Incidence of new CILs (70.6% vs. 85.7%,ip/i= 0.022), number of lesions (2.0 vs. 3.0,ip/i= 0.010), and lesions volume (105.0 mmsup3/supvs. 200.0 mmsup3/sup,ip/i= 0.047) was significantly lower in the non-calcific AS group. However, the maximum and average lesion volumes were comparable between two groups. Non-calcific AS was associated with lower risk for developing new CILs by univariate logistic regression analysis [Odds ratio (OR): 0.040, 95% confident interval (CI): 0.18-0.90,ip/i= 0.026] and multivariate analysis (OR: 0.031, 95% CI: 0.13-0.76,ip/i= 0.010). In summary, non-calcific AS patients had a lower risk of developing new cerebral ischemic infarction after TAVI compared to calcific AS patients. However, new ischemic lesions were still found in over 70% of patients.

The metabolic alterations of amino acid metabolism are closely associated with inflammatory response. However, relatively little is known about the roles of phenylalanine (Phe)/tyrosine (Tyr) catabolites during inflammation. Nitisinone (NTBC) is an orphan drug used to treat hereditary tyrosinemia type I potentially by changing Phe/Tyr metabolic flow. In this study, we used NTBC as a tool to investigate the potential role of the Phe/Tyr catabolic pathway in inflammatory responses. We found that NTBC was effective in tempering the bacterial endotoxin lipopolysaccharide (LPS)-induced septic shock in mice. Mechanistically, the protective effect was related to the accumulation of a Phe/Tyr catabolic intermediate, 4-hydroxyphenylpyruvate (4-HPP), induced by the NTBC treatment. 4-HPP could inhibit NLRP3 inflammasome priming and activation processes and therefore reduce IL-1β release and pyroptosis. Like NTBC, 4-HPP was also effective in attenuating endotoxic shock in mice. Our results suggest the Phe/Tyr catabolic pathway as a potential immunoregulatory hub that may be exploited therapeutically to alleviate inflammation.

In this work, a new N-halamine precursor with two epoxy groups, 1,3-bis(2,3-epoxypropyl)-s-triazine-2,4,6-trione (BETT), was synthesized and used to enhance the compatibility between poly(lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT). The rheological analysis and GPC indicated that chain extension between PLA and PBAT occurred during the melt-blending in the presence of BETT. The PLA/PBAT chain extensions improved the compatibility between PLA and PBAT and hindered the crystallization of PLA. SEM images showed that PLA/PBAT blend gradually changed from the typical sea-island phase without BETT to a co-continuous structure with increase in amount of BETT. This showed that the interfacial compatibility between PLA and PBAT improved significantly on addition of BETT. Moreover, compared to PLA/PBAT blend, the mechanical properties of PLA/PBAT/BETT blends showed great improvement. Furthermore, the chlorinated PLA/PBAT/BETT sheets displayed excellent antibacterial activities against E. coli (CMCC 44103) and S. aureus (ATCC 6538) cultures, wherein the sheets with 17.5 ± 0.8 μg/cm2 of the active chlorine could kill all inoculated bacteria within 30 min.

It is considered that intestinal barrier dysfunction and systemic endotoxemia drive obesity and its related complications. However, what causes barrier dysfunction remains to be elucidated. Here, we showed that the gut microbiota from high-fat diet (HFD)-fed mice had impaired ability to degrade dietary flavonoids, and in correspondence, the microbial-derived flavonoid metabolite desaminotyrosine (DAT) was reduced. Supplementation of DAT in the drinking water was able to counter the HFD-induced body fat mass accumulation and body weight increment. This is correlated with the role of DAT in maintaining mucosal immune homeostasis to protect barrier integrity. DAT could attenuate dextran sodium sulfate (DSS)-induced mucosal inflammation in a type I interferon signal-dependent manner. Furthermore, intraperitoneal injection of DAT-protected mice from bacterial endotoxin-induced septic shock. Together, we identified DAT as a gut microbiota-derived anti-inflammatory metabolite that functions to modulate local and systemic immune homeostasis. Our data support the notion of dysbiosis being an important driving force of mucosal barrier dysfunction and systemic metabolic complications.

Toxigenic Clostridium difficile (C. difficile) is the main cause of antibiotic-associated diarrhea and can induce pseudomembranous colitis and infrequent toxic megacolon, which are potentially fata...

Protein-based adhesives have gained considerable interest, due to their unique ecofriendliness and abundant functional groups. However, the presence of polar groups results in poor water resistance...

Recent progress indicates that the gut microbiota plays important role in regulating the host's glucose homeostasis. However, the mechanisms remain unclear. Here, we reported that one integral member of the murine gut microbiota, the protozoan

The herpes virus entry mediator (HVEM) is an immune checkpoint molecule regulating immune response, but its role in tissue repair remains unclear. Here, we reported that HVEM deficiency aggravated hepatobiliary damage and compromised liver repair after 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced injury. A similar phenotype was observed in B and T lymphocyte attenuator (BTLA)-deficient mice. These were correlated with impairment of neutrophil accumulation in the liver after injury. The hepatic neutrophil accumulation was regulated by microbial-derived secondary bile acids. HVEM-deficient mice had reduced ability to deconjugate bile acids during DDC-feeding, suggesting a gut microbiota defect. Consistently, both HVEM and BTLA deficiency had dysregulated intestinal IgA responses targeting the gut microbes. These results suggest that the HVEM-BTLA signaling may restrain liver injury by regulating the gut microbiota.

FTL10 is an early-flowering mutant of rice (Oryza sativa L.) with a premature senescent phenotype. Early leaf senescence can cause negative effects on rice yield. Moreover, rice leaves are damaged under high-light conditions, which promote rice senescence. Artificial shading can reduce the amount of light absorbed by rice leaves. The aim of this study was to investigate the effects of shading at noon (11:30–14:00) on the senescence and yield of FTL10. The results showed that shading improved the total antioxidant capacity of rice leaves, reduced the accumulation of reactive oxygen species (ROS) and reduced the expression of genes related to senescence. In the shaded group, the degradation rate of chlorophyll and Rubisco proteins, which are related to photosynthesis, was relatively slow, and the photosynthetic rate was relatively high. Compared with those under the natural growth conditions, the proportion of photosynthetic electron allocated to photorespiration in the shaded group rice leaves was lower, and the proportion allocated to carbon fixation was higher. The yield data showed that the single-spike weight and yield per plant of rice significantly increased after shading. Therefore, our research shows that shading at noon could delay FTL10 senescence and increase yields.

Background Tyrosine kinase inhibitors (TKIs) can significantly prolong overall survival for patients with advanced non‐small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR)‐mutation or anaplastic lymphoma kinase (ALK)‐rearrangement. However, the real‐world evaluation status of ALK/EGFR in China remains unclear. Methods We conducted a prospective study including 1134 patients with cytologically or histologically confirmed advanced NSCLC (stage IIIb–IV) at 12 Chinese hospitals. Results The most common evaluation methods were amplification‐refractory mutation system for EGFR status and immunohistochemistry targeting D5F3 for ALK status. Among patients with non‐squamous, the EGFR mutation rate was 44.1% and the ALK rearrangement rate was 10.0%. Among patients with squamous cell carcinoma, the EGFR mutation rate was 8.3% and the ALK rearrangement rate was 3.7%. Among all patients, gender (HR = 1.7, 95%CI = 1.2–2.4, P = 0.006), smoking history (HR = 1.8, 95%CI = 1.3–2.7, P = 0.001), histology (HR = 5.0, 95%CI = 2.4–10.1, P < 0.001), and brain metastases (HR = 1.5, 95%CI = 1.1–2.2, P = 0.017) were independent predictors of EGFR mutation, while age (HR = 2.6, 95%CI = 1.7–4.1, P < 0.001) was an independent predictor of ALK rearrangement. The median time from tumor diagnosis to EGFR or ALK status confirmation was 7 and 5 days, respectively. Targeted therapy rate was 73.8% in EGFR‐positive patients and 51.4% in ALK‐positive patients. There was a negative correlation between the first‐line targeted therapy rate and the EGFR mutation detection period (r = −0.152, P = 0.02), while no significant correlation among patients with ALK rearrangement (r = −0.179, P = 0.076). Conclusion Squamous NSCLC patients should also be routinely tested to determine their EGFR/ALK statuses. The first‐line targeted therapy rate remains low in Chinese patients with NSCLC.

In this study, zein, a renewable natural biopolymer from corn, was used to prepare a new biodegradable material with poly(butylene adipate-terephthalate) (PBAT) by reactive blending in the presence of poly(ethylene glycol diglycidyl ether) (PEGDGE). The effects of blending temperature and zein content on the morphology and mechanical and thermal properties of PBAT/zein blends with or without PEGDGE were investigated. Because of the high reactivity of the epoxy group in PEGDGE, the interfacial compatibility between zein and PBAT was improved greatly, and zein exhibited as a spheral phase with smaller size and finer dispersion in the PBAT matrix after the introduction of PEGDGE. Therefore, PEGDGE served as a plasticizer and reactive compatibilizer in the PBAT/zein blending system. Both the tensile strength and elongation at break of the blends with PEGDGE were improved greatly compared with those of the blends without PEGDGE but decreased gradually with the increase of zein content. These findings may provide a feasible way to utilize zein widely, and the new biodegradable blends with excellent stretchability could be used as packing materials in the future.

Efficient capture of radioactive iodine (129I, 131I) is of great significance in spent fuel treatment. In this paper, a new adsorbent named Catechin@ACF was successfully prepared through interface assembly of specific recognition gripper with plant polyphenols (catechin) on activated collagen fiber (ACF), and the catechin membrane with specific grip on iodine was successfully constructed on the surface of ACF. The results showed that the adsorbent assembled catechin membrane was rich in aromatic rings, hydroxyl groups and imine adsorption sites, and possessed specific recognition and capture characteristics of iodine. Moreover, the as-prepared Catechin@ACF showed excellent capture capacity for iodine vapor and iodine in organic solution with the maximum capture capacity of 2122.68 mg/g and 258.29 mg/g, respectively. In iodine-cyclohexane solution, the adsorption process was in according with the Pseudo first order kinetic and Langmuir isothermal model. In addition, the specific recognition and capture mechanism analysis indicated that the aromatic rings, phenolic hydroxyl groups and imine groups in the catechin membrane were the specific and effective grippers for iodine, and finally iodine formed a stable conjugated system with the adsorbent in the form of I- and I3-. Therefore, the as-prepared specific iodine capturer Catechin@ACF was expected to play a vital role in the capture of radioactive iodine in spent fuel off-gas because of its specific recognition, high capture capacity, large-scale preparation, and environment-friendly.

Extraction uranium from complicated aqueous solutions (seawater and nuclear wastewater) has been promoting the development of multi-functional adsorbents with high adsorption capacities and high selectivity. Here, we proposed a co-immobilization approach to preparing uranium adsorbents. Due to specific recognition and binding between functional groups, bayberry tannin (BT) and hydrous titanium oxide (HTO) were co-immobilized onto nano collagen fibrils (NCFs). The adsorption performances of NCFs-HTO-BT to uranium were systematically investigated in two aqueous systems, including nuclear wastewater and seawater. Results proved that NCFs-HTO-BT possessed the remarkable adsorption capacities and affinities for uranium in wastewater (393.186 mg g−1) and spiked seawater (14.878 mg g−1) with the uranium concentration of 320 mg g−1 and 8 mg g−1, respectively. Based on characteristic analysis of the adsorbent before and after uranium adsorption, the hydroxyl groups of HTO, the adjacent phenolic hydroxyl groups of BT, and nitrogen-containing and oxygen-containing functional groups of NCFs were active sites for uranium adsorption.

A significant breakthrough in the field of obesity research was the demonstration that an obese phenotype could be manipulated by modulating the gut microbiota. An important next step is to elucidate a human-relevant "map'' of microbiota-host interactions that regulate the metabolic health of the host. An improved understanding of this crosstalk is a prerequisite for optimizing therapeutic strategies to combat obesity. Intestinal mucosal barrier dysfunction is an important contributor to metabolic diseases and has also been found to be involved in a variety of other chronic inflammatory conditions, including cancer, neurodegeneration, and aging. The mechanistic basis for intestinal barrier dysfunction accompanying metabolic disorders remains poorly understood. Understanding the molecular and cellular modulators of intestinal barrier function will help devise improved strategies to counteract the detrimental systemic consequences of gut barrier breakage. Changes in the composition and function of the gut microbiota, i.e., dysbiosis, are thought to drive obesity-related pathogenesis and may be one of the most important drivers of mucosal barrier dysfunction. Many effects of the microbiota on the host are mediated by microbiota-derived metabolites. In this review, we focus on several relatively well-studied microbial metabolites that can influence intestinal mucosal homeostasis and discuss how they might affect metabolic diseases. The design and use of microbes and their metabolites that are locally active in the gut without systemic side effects are promising novel and safe therapeutic modalities for metabolic diseases.

Background Well-designed mobile health (mHealth) interventions support a positive user experience; however, a high rate of disengagement has been reported as a common concern regarding mHealth interventions. To address this issue, it is necessary to summarize the design features that improve user engagement based on research over the past 10 years, during which time the popularity of mHealth interventions has rapidly increased due to the use of smartphones. Objective The aim of this review was to answer the question “Which design features improve user engagement with mHealth interventions?” by summarizing published literature with the purpose of guiding the design of future mHealth interventions. Methods This review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist. Databases, namely, PubMed, Web of Science, Cochrane Library, Ovid EMBASE, and Ovid PsycINFO, were searched for English and Chinese language papers published from January 2009 to June 2019. Thematic analysis was undertaken to assess the design features in eligible studies. The Mixed Methods Appraisal Tool was used to assess study quality. Results A total of 35 articles were included. The investigated mHealth interventions were mainly used in unhealthy lifestyle (n=17) and chronic disease (n=10) prevention programs. Mobile phone apps (n=24) were the most common delivery method. Qualitative (n=22) and mixed methods (n=9) designs were widely represented. We identified the following 7 themes that influenced user engagement: personalization (n=29), reinforcement (n=23), communication (n=20), navigation (n=17), credibility (n=16), message presentation (n=16), and interface aesthetics (n=7). A checklist was developed that contained these 7 design features and 29 corresponding specific implementations derived from the studies. Conclusions This systematic review and thematic synthesis identified useful design features that make an mHealth intervention more user friendly. We generated a checklist with evidence-based items to enable developers to use our findings easily. Future evaluations should use more robust quantitative approaches to elucidate the relationships between design features and user engagement.

Immune and nervous system sensing are two important ways of detecting inner and outer environmental changes. Immune cell activation in the gut can promote metabolic disorders. However, whether enteric nervous system sensing and activities are also important in metabolic syndromes is not clear. Enteric glial cells (EGCs) are thought to have sensing ability, but little is known about the potential connections between EGC and metabolic disorders. Consuming a modern Western-type high-fat low-fiber diet increases the risk of obesity. Here, we reported that dietary shift from a normal chow diet to a high-fat diet in wild-type (WT) C57BL/6 mice induced a transient emergence of glial fibrillary acidic protein (GFAP)-positive EGC network in the ileal lamina propria, accompanied by an increase of glial-derived neurotrophic factors production. Inhibition of EGC metabolic activity via gliotoxin fluorocitrate or glial-intrinsic deletion of myeloid differentiation factor 88 (Myd88) in mice blocked this dietary change-induced activity. Furthermore, we found a different role of MYD88 in glial cells versus adipocyte in diet-induced obesity. The glial Myd88 knockout mice gained less body weight after HFD feeding compared to the littermate controls. In contrast, adipocyte deletion of Myd88 in mice had no impact on the weight gain but had exacerbated glucose metabolic disorders. Pharmacological interventions of glial activities by fluorocitrate prevented body weight gain in a dietary type- and glial MYD88-independent manner. Collectively, our data reveal a previously unappreciated function of EGC in sensing a dietary shift-induced perturbation and glial activities as a whole may play roles in diet-induced obesity.New & NoteworthyIt is known that obesity and its related metabolic syndrome can damage the neuronal system. However, whether the neuronal system also participates in the development of obesity is unclear. Diet is an important contributing factor to obesity. Our study reveals that consuming a high-fat diet can induce a transient enteric glial cell response via its intrinsic sensing molecule(s). Inhibiting overall glial cell activities may have an impact on the development of the metabolic syndrome.

BACKGROUND Well-designed mobile health (mHealth) interventions support a positive user experience; however, a high rate of disengagement has been reported as a common concern regarding mHealth interventions. To address this issue, it is necessary to summarize the design features that improve user engagement based on research over the past 10 years, during which time the popularity of mHealth interventions has rapidly increased due to the use of smartphones. OBJECTIVE The aim of this review was to answer the question “Which design features improve user engagement with mHealth interventions?” by summarizing published literature with the purpose of guiding the design of future mHealth interventions. METHODS This review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist. Databases, namely, PubMed, Web of Science, Cochrane Library, Ovid EMBASE, and Ovid PsycINFO, were searched for English and Chinese language papers published from January 2009 to June 2019. Thematic analysis was undertaken to assess the design features in eligible studies. The Mixed Methods Appraisal Tool was used to assess study quality. RESULTS A total of 35 articles were included. The investigated mHealth interventions were mainly used in unhealthy lifestyle (n=17) and chronic disease (n=10) prevention programs. Mobile phone apps (n=24) were the most common delivery method. Qualitative (n=22) and mixed methods (n=9) designs were widely represented. We identified the following 7 themes that influenced user engagement: personalization (n=29), reinforcement (n=23), communication (n=20), navigation (n=17), credibility (n=16), message presentation (n=16), and interface aesthetics (n=7). A checklist was developed that contained these 7 design features and 29 corresponding specific implementations derived from the studies. CONCLUSIONS This systematic review and thematic synthesis identified useful design features that make an mHealth intervention more user friendly. We generated a checklist with evidence-based items to enable developers to use our findings easily. Future evaluations should use more robust quantitative approaches to elucidate the relationships between design features and user engagement.